Biomedical subjects

M M Large

Publications and source records attributed to M M Large.

6 recordsLinked to original sources

PubMed2003

Human brain regions required for the dividing and switching of attention between two features of a single object.

This combined PET and ERP study was designed to identify the brain regions activated in switching and divided attention between different features of a single object using matched sensory stimuli and motor response. The ERP data have previously been reported in this journal [64]. We now present the corresponding PET data. We identified partially overlapping neural networks with paradigms requiring the switching or dividing of attention between the elements of complex visual stimuli. Regions of activation were found in the prefrontal and temporal cortices and cerebellum. Each task resulted in different prefrontal cortical regions of activation lending support to the functional subspecialisation of the prefrontal and temporal cortices being based on the cognitive operations required rather than the stimuli themselves.

Adult↗

PubMed2001

Relationship between compensation claims for psychiatric injury and severity of physical injuries from motor vehicle accidents.

OBJECTIVE: To examine the relationship between compensation claims for psychiatric injury after motor vehicle accidents and physical injuries sustained. DESIGN: Audit of Compulsory Third Party (CTP) insurance claims. SUBJECTS AND SETTING: 559 consecutive CTP claims referred by NRMA Insurance Limited to its sole provider of CTP legal services during a three-month period in 1994 after the claimant had engaged legal representation. MAIN OUTCOME MEASURES: Claim for psychiatric injury (any psychiatric disorder excluding traumatic brain injury) supported by a medicolegal report from a psychiatrist, other medical practitioner or psychologist; pre-existing psychiatric disorders; Injury Severity Score; initial treatment setting; hospital stay; percentage of accidents involving loss of consciousness or a death. RESULTS: 522 claims were eligible for the study; 19.5% (102/522) included a claim for psychiatric injury. A pre-existing depression or anxiety disorder was documented in 11 claims (2.1% of all claims and 3.9% of those claiming psychiatric injury). Only very severe injuries, particularly those involving loss of consciousness, were associated with an increased rate of claims for psychiatric injury. CONCLUSIONS: No association was found between claims for psychiatric injury and severity of physical injuries, except among those most severely injured.

Accidents, Traffic↗

PubMed2001

Human cortical processing of colour and pattern.

The present study investigates human visual processing of simple two-colour patterns using a delayed match to sample paradigm with positron emission tomography (PET). This study is unique in that we specifically designed the visual stimuli to be the same for both pattern and colour recognition with all patterns being abstract shapes not easily verbally coded composed of two-colour combinations. We did this to explore those brain regions required for both colour and pattern processing and to separate those areas of activation required for one or the other. We found that both tasks activated similar occipital regions, the major difference being more extensive activation in pattern recognition. A right-sided network that involved the inferior parietal lobule, the head of the caudate nucleus, and the pulvinar nucleus of the thalamus was common to both paradigms. Pattern recognition also activated the left temporal pole and right lateral orbital gyrus, whereas colour recognition activated the left fusiform gyrus and several right frontal regions.

Adult↗

PubMed1999

An exploration of varieties of visual attention: ERP findings.

A set of five tasks was designed to examine dynamic aspects of visual attention: selective attention to color, selective attention to pattern, dividing and switching attention between color and pattern, and selective attention to pattern with changing target. These varieties of visual attention were examined using the same set of stimuli under different instruction sets; thus differences between tasks cannot be attributed to differences in the perceptual features of the stimuli. ERP data are presented for each of these tasks. A within-task analysis of different stimulus types varying in similarity to the attended target feature revealed that an early frontal selection positivity (FSP) was evident in selective attention tasks, regardless of whether color was the attended feature. The scalp distribution of a later posterior selection negativity (SN) was affected by whether the attended feature was color or pattern. The SN was largely unaffected by dividing attention across color and pattern. A large widespread positivity was evident in most conditions, consisting of at least three subcomponents which were differentially affected by the attention conditions. These findings are discussed in relation to prior research and the time course of visual attention processes in the brain.

Adolescent↗

PubMed1998

Further evidence for a deficit in switching attention in schizophrenia.

In this study, sustained, selective, divided, and switching attention, and reloading of working memory were investigated in schizophrenia by using a newly developed Visual Attention Battery (VAB). Twenty-four outpatients with schizophrenia and 24 control participants were studied using the VAB. Performance on VAB components was correlated with performance of standard tests. Patients with schizophrenia were significantly impaired on VAB tasks that required switching of attention and reloading of working memory but had normal performance on tasks involving sustained attention or attention to multiple stimulus features. Switching attention and reloading of working memory were highly correlated with Trails (B-A) score for patients. The decline in performance on the switching-attention task in patients with schizophrenia met criteria for a differential deficit in switching attention. Future research should examine the neurophysiological basis of the switching deficit and its sensitivity and specificity to schizophrenia.

Adult↗

PubMed1995

Jumping from a general hospital.

Jumping is the most common reported means of suicide in general hospitals. There have been no published reviews of suicides of nonpsychiatric inpatients since 1980. We describe 12 subjects who, between January 1980 and January 1992, jumped from a large general teaching hospital. Eight of them succumbed, providing a rate of suicide of 1.7 per 100,000 admissions. There were three clinical subgroups: those admitted after suicide attempts, the acutely delirious, and the chronically medically ill. Factors appearing frequently in the third subgroup were pain, dyspnea, transient confusion, poor prognosis, and recent adverse news. When we compared the hospital jumpers with 30 nonfatal jumpers who attended our Emergency Department, the medical and psychiatric profiles differed in the frequency of medical illnesses, advancing age, male gender, and absence of preexisting psychiatric illness. Proximity and ease of access to balconies and windows appeared to be highly relevant to the prevention of hospital jumping.

Adolescent↗